textproduct: Quad Cities

KEY MESSAGES

- Areas of drifting snow (patchy blowing snow?) are possible through midday, as SSW winds gust 20-30 mph.

- Warm up over the next few days resulting in snow melt and the potential for fog and re-freeze at night

- Thursday, a strong system will bring a 40-60% chance for measurable rain (trends support higher probabilities) with mainly light amounts (<0.25 inch). Also, a period of gusty winds is likely with 40-50% probabilities for gusts over 40 mph.

UPDATE

Issued at 551 AM CST Mon Dec 15 2025

Despite winds turning gusty this morning, wind chills are improving above hazardous criteria as temperatures gradually rise. As a result, the Cold Weather Advisory for west central Illinois will be allowed to expired at 6 AM.

SHORT TERM /THROUGH TONIGHT/

Issued at 254 AM CST Mon Dec 15 2025

Early morning surface analysis places high pressure from the Ohio Valley through the Lower Mississippi Valley with low pressure over North Dakota. An increasing pressure gradient between these two features will continue to drive an increase in southerly low level flow today with breezy SSW winds, along with substantial warm air advection. While the full brunt of the warmth is likely to remain just off the surface due to the snow cover and despite some high level cloudiness, temperatures should still recover nicely and in fact look to warm by 20-30 degrees from current early morning temperatures. NBM 10th percentile for highs (9 in 10 chance of being higher) range from the lower 20s northeast to the lower 30s southwest. With the gusty winds today we can't rule out the potential for some drifting snow and patchy blowing snow, particularly in the open rural areas south of Hwy 30 which received 2-8 inches of snow on Saturday. Confidence is low however, especially with any blowing snow due to the snow age being 48+ hours and this is supported by the Baggaley blowing snow model which for temps in the 20s and winds up to 29 kt offer drifting snow as the only impact and this may be lower grade, but nonetheless something to keep an eye on for at least through midday before temperatures make a push toward the freezing mark. East-west roadways in the open/rural areas would be the most susceptible to any drifting, and patchy blowing snow? A special weather statement was issued for this potential through 18z today.

Tonight, the primary concern is with fog ahead of a lifting warm front. The fog could be rather dense with the 00z HREF depicting a rather large footprint of 40-60% probabilities for visibilities less than a half mile. Several hi-res models also depict a rather strong signal for fog via surface visibility plots including the HRRR, NAM 4km Nest and HiResW-ARW although there's some differences on areal extent/focus between primarily north of I-80 and then along/south of Hwy 30 with the snow cover which seems more reasonable. I've opted to add fog mention areawide overnight through mid-morning Tuesday, more patchy to the north and areas to south where the warmer temperatures and greater snow melt potential will exist. Will have to watch for any moisture deposition with the fog given surface temperatures likely to be below freezing. Hard to pin down this potential as this juncture. I will say I'd prefer to see better moisture advection than what is being suggested, which is very little. For that reason I feel this is a very low potential at this time, but something to monitor.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 254 AM CST Mon Dec 15 2025

We'll continue to see a decent warm-up through mid-week, as upper ridging builds toward the region. Temperatures are anticipated to climb near or even a bit above climatological normals, with the magnitude of warm-up dependent upon extent of snow cover. Again, much of the warmth will likely remain just off the surface, but still milder temperatures well into the 30s and 40s and lots of thaw/melt taking place Tuesday and Wednesday. A weak cold front/ surface trough is suggested to swing through the region Tuesday afternoon into evening attendant to a quick wave passing to our north. Soundings continue to suggest considerable dry air above low level saturation limiting any measurable rain potential, but if the saturation depth is sufficient it could lead to some drizzle and also fog.

Wednesday night into Thursday the focus is with a fairly strong shortwave trough and attendant deepening surface low shifting across the Northern Plains and Upper Mississippi Valley, eventually ushering a strong cold front through the region. Ahead of this system on Wednesday night we'll see breezy southerly winds develop leading to strong moisture advection with a connection to the Gulf aided by a 50+ kt LLJ. This will foster a non-diurnal temperature trend or rising temperatures through the night. Confidence continues to increase that we'll see a round of showers with this system. However, the trough remains quite progressive and thus is likely to limit precipitation amounts. Latest NBM 24 hour probabilities ending Thursday evening for greater than 0.25 inch are 20-40%, mainly east of the Mississippi River. That being said, there is still a small signal in ensemble clusters and within individual members for a slower/deeper trough. If that were too occur it would allow for longer residence time of deeper moisture and result in the potential for higher rain amounts. Something else to monitor given the strong dynamics is the potential for thunderstorms, again highly dependent upon speed of the system. Currently the consensus toward a more progressive system leads to marginal moisture and limited instability and keeps this potential very low (<20%).

As the cold front sweeps through on Thursday, there is a chance that some wrap-around snow or mix could brush parts of the area but this would appear to be a very low impact. What is potentially looking to be more impactful is the winds given rather anomalously strong winds (50-60 kt) at 850 hPa and steepening low level lapse rates, which coupled with strong cold advection could foster a period of strong winds. NBM probabilities depict areas of 40-50% for wind gusts greater than 40 mph Thursday afternoon. Also worth noting the NBM and LREF 75th and 90th percentile wind gusts which are 45 to near 50 mph. Will be needing to keep an eye on this potential for wind headlines. A quick hitting shot of very cold air is also expected post frontal for Thursday night as 850 hPa temperatures plunge to between -14c and -18c for a time. This will support lows in the single digits and teens and enough wind to lower wind chills into the single digits above/below zero.

Heading into next weekend we look to keep the roller coaster on temperatures going with a warm-up Friday into Saturday ahead of another northern CONUS trough. This looks to bring another cold front through Saturday/early Sunday and a temperature drop only back to around or slightly below normal. Then, potentially an even stronger warm-up appears as we head toward Christmas, with the Climate Prediction Center (CPC) latest 8-14 Day temperature outlook (Dec 22-28) showing 60-70% probabilities for above normal temperatures.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 530 AM CST Mon Dec 15 2025

VFR conditions are expected into this evening with mainly high level cloudiness and CIGs above 12kft agl. LLWS mention will continue over the next few hours with SW winds of 40-45+ kts near 2kft agl. Eventually this will diminish as surface winds continue to become gusty at 15-25 kts from S/SW today. These gusty winds may foster some low grade drifting and possibly patchy blowing snow, but too much uncertainty on occurrence and impacts for any mention given the snow age being 48+ hours old. Winds look to gradually diminish this afternoon into tonight and may go light/variable or light southerly ahead of a warm front. There's a consensus signal in the guidance for fog tonight, but uncertainty with spatial extent/location with some north of I-80 seemingly more radiational cooling affects and others south of I-80 more snowmelt. The fog could be dense with 00z HREF probabilities of visibilities <0.5 mile at 40-60% and a fairly large footprint across all of the terminals. There is also potential for some high cloudiness which if occurs could play a pivotal role in extent of any fog development. Given the uncertainty on extent but with the fairly high signal for fog I opted to start by introducing MVFR visibilities after 06-08z at the sites and let later shifts refine as more details are known.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.